Papers by Keyword: Tool Life

Abstract: Inconel 625 alloy consisting of Ni and Cr and others has advantageous properties such as heat resistance and corrosion resistance, which make it a suitable material for application in aerospace, energy, and marine industries. However, it is also a difficult-to-machine material because of factors such as work hardening, low thermal conductivity, and high tool affinity. Therefore, the problems of the tool wear, chipping, and adhesion often occur in milling of Inconel 625 alloy using end mills. In this study, the milling of Inconel 625 was conducted using coated cemented carbide end mills, and the cutting conditions with the high efficiency were investigated under three rotational speeds and four feed rates. The results showed that increasing the feed rate increased the surface roughness, but did not increase the tool life. In addition, the results also showed that increasing the rotational speed did not increase the tool life, but reduced the surface roughness. As a result, the effects of the rotational speeds and feed rates on the tool life were clarified.

Abstract: Hard materials are widely used in industry due to qualities such as strong fatigue strength and the ability to maintain strength at a high temperature. Still forming certain raw materials into the appropriate shapes is the challenge in subtractive manufacturing industries and these materials are categorized as hard to machine material. To solve this problem Heat Assisted Machining (HAM) is an emerging and most dominating method, which requires an external heat source subjected to the workpiece either before or during the machining to increase the ductility. As a result, the workpiece yield and shear strength are reduced. This is an advanced technique to enhance the tool’s life, and productivity. The present paper provides in-depth knowledge of thermal assisted machining process where various heat sources are used like laser, plasma, LPG, Induction heating and etc. The comparison analysis between various heat sources is made and their impact on various parameters like tool wear, material removal rate, surface roughness, stability and etc. were illustrated and provide the novel approach for selecting the correct heat-assisted technique which is used for turning process in order to increase the machining process.

Abstract: In cold forging processes, diamond-like carbon (DLC) coatings have become established as a wear protection for forging dies, featuring high hardness and advantageous friction properties. This counteracts the particular critical abrasive tool wear and increases tool life. A major disadvantage of DLC coatings is their low thermal stability. In this study, the influence of metallic elements (niobium, tungsten and chromium) in the treatment atmosphere of the coating process is investigated with the aim of increasing the temperature resistance of the DLC coating and enabling its application as a wear-protection measure for hot forging dies. Preliminary studies were carried out to investigate the influence of different treatment atmospheres on wear-reducing properties such as high hardness and coating adhesion depending on prior nitriding processes. The most promising metal-doped DLC coating, with 30 % tungsten in the treatment atmosphere, was used in serial forging tests. At a blank temperature of 1,200 °C and a moderate count of 100 forging cycles, wear was reduced by up to 60 % compared to the nitrided reference tool.

Abstract: Forging tools must be able to withstand very strong mechanical, thermal, tribological, and chemical stresses. The extent to which a tool can withstand these stresses depends on the material used and its pre-treatment as well as the heat and surface treatment, i.e. the load capacity. The ratio of stress to load capacity determines how high the tool life of a forging tool is. This paper deals with the variations in the tool life of forging tools using the example of a specific industrial stage sequence and production conditions. Due to a large number of influencing variables that have an effect on the tool during the entire tool life history, the focus of this work is placed on influencing variables of the forming process. Based on real production parameters of a forging company, which are recorded during a period for the investigation, the process data are analyzed about an influence on the tool life. The investigation focuses on four influencing variables, namely the subjective assessment of the end of the tool life, the interaction between the forming stages, production interruptions, and the cooling and lubrication of the forming tools. For the parameters that are not yet recorded during the trials, promising available measurement methods are identified and tested under laboratory conditions. One example of this is the recording of the actual spray quantities that are sprayed onto the tool surface before the forming process. The results of the investigations show that the tool life fluctuations can be reduced by about 16% and as a consequence, the average tool life can be increased by about 13%.

Abstract: Metal cutting is the commonly used method in mechanical design, and the tool is the most important key factor in metal cutting. When the tool is severely worn, it will cause the tool to break. This article takes the current value of machining precision turret as an example to study the relationship between current value and tool wear. We used statistical mathematical models to predict tool life and used scatter diagrams to verify the timing of tool change and the actual degree of tool wear, to achieve accurate prediction and reduce tool waste. In our experiment, the core part of the indexing plate (turret) is machined by the horizontal machining center, The CCD image capture system was utilized to evaluate cutting tool wear. Three methods are analyzed to predict tool wear and current. The probability statistical mathematical model shows good match to predict the tool life. it is possible to find out the holes with poor quality caused by tool wear and calculate the exchange rate.

Abstract: This paper describes a temperature stabilization method in dry metal cutting. Using a hidden phase transfer heat allows to significantly reduce the wear rate. The tool holder design with porous evaporative cooling system is presented. Dependences of tool life of cutters on the cutting speed without cooling and with porous cooling are shown. This approach could be advantageous for the cutting of hard materials (titanium alloy).

Abstract: Hadfield steel is widely used in the manufacture of machines and mechanisms operating in harsh conditions. When machining Hadfield steel parts, problems are due to the strain hardening. The article studies the influence of cutting modes on steel hardness, tool thrust and surface roughness when milling Hadfield steel using cutters with replaceable inserts. The experiments were conducted on a milling machining center using high-productivity cutting tools. The optical roughness measuring method was applied. Hardness was measured with a portable hardness tester before and after milling. The article describes experimental results that show the dependence of the output machining parameters on the cutting speed and feed per tooth. The influence of cutting data on tool life in a finish milling operation was identified. The results will help to improve the quality and productivity and increase the tool life in roughing and finishing Hadfield steel parts.

Abstract: The article deals with the determination of the efficiency of a multi-bladed tool equipped with inserts made of oxide-carbide cutting ceramics, depending on the microstructural parameters of the tool material. The microstructural parameters of the oxide-carbide cutting ceramic, which affect the performance of the tool, are proposed to be determined according to the electrical resistance of the tool material. In order to implement the method for determining the working capacity of the instrument, a basic design of the device for measuring the electrical resistance of the material of the instrument is proposed. The device for measuring the electrical resistance of ceramic plates consists of a body made of a dielectric material, with channels for supplying a conductive material and a groove for installing a case with a test sample. During the test, the channels are filled with a liquid conductive material, which fills the cavity formed by the channel of the case, the groove of the case and the plate itself under test. To ensure uniform filling of the cavity, after the introduction of the liquid conductive material, metal balls are installed into the channels, which are made in such a size as to ensure free sliding along the channel, but not to let the liquid pass into the upper part of the channel. The tested ceramic plate is installed in the walls of the removable case. The walls of the removable case include electrodes, which, when the device is in operation, are inserted into a cavity with a liquid conductive material at one end, and are connected to an ohmmeter at the other. Using a device for measuring the electrical resistance of ceramic plates, it is possible to determine the operability of the tool and guarantee its operation without rejection for a certain period of time, which was confirmed by experimental research in the milling of workpieces of machine parts made of gray cast iron. Experimental studies in multi-edge machining with cutters with different values ​​of electrical resistance of ceramic plates made it possible to plot graphs of the dependence of the quality of machining during milling on the operability of the tool and on the time of the machining process.

Abstract: The heat generation and subsequent temperature rise in the cutting zone due to plastic deformation and friction at tool-chip-workpiece interface are critical parameters that have a significant impact on tool wear, tool life and surface integrity. This paper aimed to analyse the effect of cutting parameters such as, cutting speed, feed and depth of cut on the cutting temperature in turning of hardened AISI 52100 alloy steel of 58 HRC using multilayer coated carbide cutting tool insert under high velocity pulsing jet minimal cutting fluid application (MCFA) environment. Response surface methodology based central composite design (CCD) was used to investigate and optimize the cutting parameters on cutting temperature response. The quadratic regression model in terms of cutting speed, feed and depth of cut for cutting temperature was developed. The diagnostic and confirmatory tests were carried out to check its validity. The implication of the process parameters and their interactions were tested using analysis of variance (ANOVA). The results showed that the cutting speed and feed were the main significant parameters affecting the cutting temperature, while depth of cut and quadratic term of cutting speed had a moderate effect. The predictive model developed indicates the 99% desirability level in turning of AISI 52100 hardened steel under the MCFA environment. The predicted values of cutting temperature response are in close agreement with the experimental results.

Abstract: The high-performance machining of difficult-to-cut stainless steel (AISI 316) demands the development and optimization of high-performance tools that can withstand tool load without compromising the surface quality of the components been produced. To justify the optimization feasibility of coated carbide tool in end milling application for good surface quality, a material removal and Productivity approach by evaluating the tool life under optimized cutting condition were carried out in this current research. The objective of this study is to optimize flank tool wear in end milling of AISI 316 using Design of Experiment and box-Behnken method. Tool wear value of 0.174mm was achieved through optimization at low values of feed, speed, and depth of cut. However, an increased feed, depth of cut and speed promised to yield better volume removed in return making tool life to be truncated faster.